In a large pot of boiling water, cook the fettucine for 8-10 minutes or until al dente. Drain well, return the cooked fettucine to the pot, and set aside. Meanwhile, in a large non-stick skillet, saute the shallots in the olive oil for 2 minutes to soften. Cut the spears of asparagus diagonally into 1-inch pieces, separating the stems and tips, and set the tips aside for later use. Add the sliced asparagus stems, carrot, and red pepper to the shallots, and saute for 2 minutes. Add the mushrooms and garlic and saute an additional 2 minutes. Add the zucchini, peas, and sun-dried tomatoes, and continue to saute the mixture until the vegetables are tender.

Add the Dijon mustard, flour, and onion powder to the pan, stir well to combine, and cook the mixture for 1 minute while stirring constantly. Add the soy milk, nutritional yeast flakes, salt, pepper, and crushed red pepper flakes, stir well to combine, and cook the mixture an additional 2-3 minutes or until thickened. Add the remaining ingredients, cover, remove the pan from the heat, and set aside for 2-3 minutes to allow the spinach to wilt. Add the vegetable mixture to the cooked fettucine and toss well to combine. Taste and adjust the seasonings, as desired. Transfer the pasta to a large bowl or platter for service.